Experimental infection of big brown bats (Eptesicus fuscus) with West Caucasian bat virus (WCBV)

Big brown bats (Eptesicus fuscus), either recently captured individuals or survivors from previous experimental infection with Irkut virus (IRKV), were inoculated with West Caucasian bat virus (WCBV), intramuscularly into the masseter (n=7) or neck (n=8) muscles, or orally (n=6). Three bats inoculated into the neck muscles developed rabies and died between days 10 and 18. Viral RNA was detected in a number of tissues but isolation was successful only from the brain. An oral swab of one of these bats was also PCR-positive, but the isolation attempt failed. Brains, salivary glands and swabs from the survivors (six months observation) were negative, as well as all blood pellets collected. Therefore, no suggestions for a carrier state or viremia were obtained. In four surviving bats inoculated in the masseter muscles, WCBV-neutralizing antibodies were detected up to the end of experiment. The absence of antibodies in the three rabid bats may be the result of shorter incubation periods. Bats infected orally neither died nor responded serologically. In the bats previously infected with IRKV, IRKV-neutralizing antibodies were detected as well, up to the end of observation (12 months after IRKV challenge), even if they were not boosted by WCBV inoculation.